Rotary blender and polisher



Nov. 16, 1965 w, CHADBOURNE ETAL 3,218,038

ROTARY BLENDER AND PQLISHER Filed Sept. 18, 1962 2 Sheets-Sheet 2INVENTORS. WILLIAM H. C'unoaouem;

BY Roy W. VIEHE ATro/IveYs.

nitecl States Patent 3,218,038 ROTARY BLENDER AND POLISHER William H.Chadbourne, North Webster, and Roy W. Vielle, West Lafayette, Ind.,assignors to Fiberfil, Inc., Warsaw, Ind., a corporation of IndianaFiled Sept. 18, 1962, Ser. No. 224,348 15 Claims. (Cl. 2593) Thisinvention relates to blenders, or machines designed for use in the drymixing of particled materials and in the tumble-polishing of pelletizedmaterials or the like. Such machines embody a hollow drum mounted forrotation about a generally horizontal axis and often provided interiorlywith flights which lift and drop the material as the drum is rotated.Blenders are of two general typesnamely, those used for treatment ofmaterial in batches and those used for the continuous treatment ofmaterial. Our invention is concerned especially with blenders of thelatter type.

Two factors which influence the design of a continuous drum-typeblender, are the distance over which it is desired that the materialfall upon release from the flights and the residence time of thematerial within the blender, the former factor determining the diameterof the blender and the latter its length. Provision for both the desireddistance of fall and residence time frequently results in blenders solarge and heavy that the rotating drum must be supported on rollers anddriven by means of high power output.

It is the primary object of our invention to provide a continuousblender in which the residence time will be independent of the axiallength of the rotating drum and can be accurately controlled. A furtherobject of the invention is to provide a blender which can be quicklyemptied and easily cleaned.

In carrying out our invention We employ a drum having a diameter such asis required to provide the desired distance of fall and a relativelyshort axial extent. This drum is rigidly mounted on a hollow shaftsupported for rotation on an axis having a slight inclination to thehorizontal and is divided into two compartments by a medial partitionperpendicular to the axis. Slots in the wall of the hollow shaft providecommunication between the interior of the shaft and each compartment,while the two compartments are interconnected by an opening in thepartition. Each compartment is provided with a circumferential series offlights which elevate and drop the material being treated as the drumrotates, such flights being so designed that each elevates material to apoint Well above the axis before discharging it. Material fed into thehigher end of the shaft passes therealong and emerges through a slot inthe shaft wall into the first compartment, where it is tumbled by theflights therein. When material builds up in the first compartment to adepth sufiicient to overlap the opening in the partition, it escapesgradually through that-opening into the second compartment, where it isfurther tumbled. The second compartment is provided with a chutepositioned and designed to receive a small proportion of the materialfalling from the flights and guide it into the hollow shaft to bedischarged. If desired, the shaft may be provided with a plurality ofaxially spaced similar drums through which the material successivelypasses before being discharged from the lower end of the shaft.

For the purpose of emptying the blender, the aforesaid chute extends tothe peripheral wall of the drum where it has a width substantially equalto the axial extent of the second compartment, and the first compartmentis provided with a chute of similar shape and disposition. The innerportion of the chute of the first compartment is covered and arranged todischarge, not directly into the 3,218,038 Patented Nov. 16, 1965 iceshaft, but into the other chute through an opening in the partitionwhich separates the two compartments. When the drum is rotated in adirection opposite to that of normal operation, the outer ends of thetwo chutes serves as scoops which pick up the material and guide it intothe shaft.

Further objects and features of our invention will become apparent fromthe following more detailed description and from the accompanyingdrawings, in which:

FIG. 1 is a side elevation of a blender;

FIG. 2 is an elevational view of one of the blender drums looking in theaxial direction of material-flow and with a portion of the drum-wallbroken away to show the interior construction;

FIG. 3 is an elevational view similar to FIG. 2 but looking in theopposite direction; and

FIG. 4 is a fragmental section through one of the drums on the line 4-4of FIG.

Referring to FIG. 1, it will be seen that the blender comprises a frame10 rotatably supporting a hollow shaft 11 on which three drums 12 arerigidly mounted in axially spaced relation. The shaft has a slightinclination to the horizontal, desirably about 5, its higher endreceiving the material to be treated, as through a supply chute 13, andits lower end being open for discharge of the material.

The three drums may be identical in construction, and it will thereforebe necessary to describe but one of them. As indicated in FIGS. 2 and 3,each drum is hexagonal in shape, although that particular shape is notessential, and is divided by a medial partition 15 into two compartmentsdesignated respectively as 16 and 17 in FIGS. 2, 3, and 4. Of the twocompartments in each drum, the compartment 16 is the one nearer theinlet end of the shaft. In each compartment are a series of flights 20which project inwardly from the peripheral wall 21 of the drum toelevate, and then drop, material as the drum rotates. The end walls ofeach drum are provided with openings through which access may be had tothe interior of the drum, each of such openings having a removable cover22, which is desirably transparent.

The flights 20 are so inclined relatively to the radial direction thatthey will elevate material to a height well above the axis of rotationand desirably at least some of them are so disposed that a portion ofthe material discharged will impinge on the shaft 11.

Within each drum, the hollow shaft 11 is provided with an elongated slot24 which overlaps both of the compartments 16 and 17. Midway of theaxial extent of such slot, the shaft is provided interiorly with apartition N 25 which is coplanar with the drum-dividing partition 15 andwhich serves to cause approaching material to pass through the slot 24into the compartment 16. Material entering the hollow shaft 11 at theinlet end thereof progresses through the shaft until it encounters thepartition 25 and passes through the slot into the compartment 16, whereit is repeatedly elevated and dropped as the drum rotates. Material fedto the compartment 16 builds up therein until it attains a depthcorresponding to the location of an opening 26 provided in the partition15. Favored by the inclination of the shaft 11, material accumulating inthe compartment 16 will escape gradually through the opening 26 into thecompartment 17, where it will be repeatedly elevated and dropped by theflights in that compartment. Residence time of the material in thecompartment 16 can be controlled by varying the number, size, and radialdisposition of the openings 26.

To effect the feeding of material from the compartment 17, thatcompartment is provided with a discharge chute 30. Such chute, which isfixed in the drum, ex-

tends along the partition from the shaft 11 to the peripheral drum-wall2t and desirably has (FIG. 3) an inner portion disposed generallyradially and an outer portion curving toward the drum wall 21 in adirection opposite to that of normal drum rotation. The chutecommunicates at its inner end with a slot 2 in the shaft 11 and has anopen side presented in a direction opposite to that in which the drumnormally rotates. For a purpose which will become apparent hereinafter,the width of the chute fail at the periphery of the drum issubstantially equal to the axial extent of the compartment 17; but inorder to lessen its tendency to trap and elevate material it desirablydecreases in Width toward the drum-axis, as shown in FIG. 4.

If the flights are disposed in the above described desirable manner,some of the material dropping from them will enter the chute 3% while itis still inclined inwardly and downwardly as indicated in FIG. 3, andmaterials so entering the chute Will flow by gravity through the slot 24into the interior of the shaft 11 where it impinges on an inclineddeflector plate 31 fixed in the shaft at an angle favoring deflection ofthe material toward the discharge end of the shaft. Material soreintroduced into the shaft feeds therealong into the compartment 16 ofthe next drum 12 or, in the case of the last drum, through the shaft tothe discharge end thereof.

As will be appreciated, the escape of material from the compartment 17in the manner just described proceeds at a relatively slow rate, sincemost of the material dropped from the upwardly moving flights Ztl willeither escape entry into the chute in falling or will enter the chutewhen it is inclined outwardly and downardly to direct the material itreceives outwardly for re-elevation rather than inwardly for dischargeinto the shaft. If, as is shown in FIG. 4, the inner end of the chute 39occupies only a portion of the slot 24 in the shaft a small proportionof falling material may enter the shaft through such slot directly whenthe slot is directed more or less upwardly. Residence time of thematerial in the compartment 1'7 is determined largely by the width ofthe inner portion of the chute 3t and by the extent of each fractionaldrum revolution during which it is both in a position to receive droppedmaterial and so inclined as to direct the received material inwardly andthrough the slot 24. For example, if the flights which immediately trailthe chute in normal rotation of the drum were narrower or disposed at asmaller angle to the radial directiton, they would drop materialearlier, a smaller proportion of the dropped material would be guidedinto the shaft, and residence time of the material in the compartment 17would be increased.

The compartment 16 is provided with a chute 34 similar in shape anddisposition to the chute 30 but differing therefrom in that its innerportion is provided with a cover 35 and discharges through an opening 36in the partition 15 either into the chute 30 or into the slot 24 on theopposite side of the shaft-partition 25. See FIG. 4. Conveniently, theopening 36 is a lobe of the otherwise circular shaft-receiving openingof the partition 15 and the obliquely disposed inner end 37 of the sidewall of the chute 34 abuts the edge of the partition 25. The cover 35extends outwardly from the inner end of the chute 34 for a distancegreat enough to prevent any material dropped by the flights 20 fromentering the chute while it is disposed in an inwardly and downwardlysloping direction, and the chute 34 therefore plays no part in normaloperation of the blender.

From the foregoing description, it will be apparent that material fedinto the inlet end of the shaft progresses therealong, enters thecompartment 16 of the drum 12 nearest the inlet end of the shaft 11, istumbled in that compartment 16, escapes through the opening 26 into thecompartment 17 of the first drum, is further tumbled in thatcompartment, and is discharged therefrom through the hollow shaft 11into the next drum 12, in

which the tumbling and feeding action is similar to that which occurredin the first drum. Material emerging from the compartment 17 of the lastdrum 12 passes through the shaft 11 to the end thereof, where it isdischarged. If desired, the shaft 11 may be provided interiorly with ahelical flight 40 promoting the feeding of material along the shaft.

Ordinarily, a blender is designed to provide a residence time so greatthat the interval required to empty the blender by continuing it inoperation after the feed of material to it has been terminated would beobjectionably long. The blender shown and described herein, however, canbe emptied quickly merely by reversing its direction of rotation. Aswill be apparent from FIGS. 2 and 3, rotation of the blender in adirection opposite to that indicated by the arrows causes the outer endsof the chutes 30 and 34 to act as scoops which pick up the loosematerial as they rotate through the lower portion of their path ofmovement and discharge the picked-up material into the hollow shaft 11as the chutes attain a position in which their inclination is downwardand inward. While, in the specific device shown, the material so fedinto the shaft from drums other than the last one must pass through oneor more additional drums before being discharged from the shaft, theemptying of the blender proceeds very rapidly.

The particular material which the specific blender shown and describedwas designed to treat is a thermoplastic molding compound in the form ofelongated granules or pellets containing longitudinally extending glassfibers. Such material is produced by impregnating and coating continuouslengths of glass strand or roving with a thermoplastic resin in liquidform, curing the resin, and then chopping the strand into pellets orgranules of H the desired length. The granules so formed possess sharpedges which would interfer with feeding of the compound in an injectionmolding machine. Further, since the glass fibers do not all break in thesame plane, short lengths of the fibers project from opposite ends ofeach granule, and such projecting fiber-ends are undesirable. Treatmentof the molding compound in the blender described rounds the sharp edgesof the granules and breaks off the projecting fiber-ends substantiallyflush with the ends of the granules. The broken-off fiber endsagglomerate in masses substantially larger than the granules of moldingcompound and can be separated therefrom by a foraminous screen providedon the discharge end of the shaft 11. The openings in such screen arelarge enough to permit passage of the granules into a first dischargechute 46 located below the screen but small enough to retain the massesof fiber-ends, which dis charge from the end of the screen 4-5 into asecond chute 47.

In a blender for use in removing projecting fiber ends frommolding-compound granules, we have found drums seven feet in diameterand one foot in axial extent to be appropriate. A shaft ill formed froma length of fiveinch pipe of one-half inch wall thickness has been foundsatisfactory to support three such drums, as shown in FIG. 1, with aspace of 18 inches between the opposed walls of adjacent drums. It willof course be understood that power-operated means (not shown) will beprovided for rotating the blender alternatively in opposite directions.

We claim as our invention:

1. A blender, comprising a hollow shaft having axially spaced inlet anddischarge openings, means supporting said shaft for rotationalternatively in first and second opposite directions about a generallyhorizontal axis, a drum having a peripheral wall and end walls rigidlymounted on said shaft between said inlet and discharge openings, saiddrum being provided with a partition disposed trans, versely to saidaxis and dividing the interior of the drum into first and secondcompartments, said shaft being provided with a first lateral openingthrough which material fed into said inlet opening may pass into thefirst compartment and with a second lateral opening through whichmaterial from the second compartment may pass into the shaft for flowtherethrough toward said discharge opening, said partition having anopening located inwardly from said peripheral wall and through whichmaterial may pass from the first compartment into the secondcompartment, said drum being provided in each compartment with flightswhich, when the drum rotates in the first direction, repeatedly elevatethe material and release it for fall to the bottom of the compartment,first and second discharge chutes located respectively in said first andsecond compartments and rigid with said drum, both said chutescommunicating at their inner ends with said second lateral shaft openingand extending generally outwardly therefrom in their respectivecompartments to the peripheral drum-wall, that side of said first chutewhich faces in the second direction of drum rotation being provided witha cover which extends from the inner end of the chute outwardly farenough to prevent entry into the chute of material falling from theflights when the drum is rotating in said first direction, the outer endof said cover being spaced from the peripheral drum-wall to provide anopening through which material can enter the chute when the drum rotatesin said second direction, that side of said second chute which faces inthe second direction of drum rotation being open for substantially itsentire radial extent, the flights in the second compartment being sodisposed relatively to the second'chute that some of the materialelevated and dropped by such flights when the drum is rotating in saidfirst direction will enter the open side of the chute while the chute isinclined inwardly and downwardly to guide the received material throughsaid second lateral shaft-opening into the interior of the shaft.

2. A blender as set forth in claim 1 with the addition of one or moreadditional and similar drums rigidly mounted on said shaft in axiallyspaced relation, the first compartment of each such additional drumreceiving material from within the shaft and the second compartmentdischarging into the shaft through its associated chute.

3. In a blender, a hollow shaft having axially spaced inlet anddischarge openings for material to be treated and supported for rotationabout a generally horizontal axis, a drum having a peripheral wall andend walls rigidly mounted on said shaft between said openings, said drumbeing provided with a partition transverse to said axis and dividing theinterior of the drum into first and second compartments, said shaftbeing provided with first and second lateral openings respectivelyconnecting said first compartment with the inlet opening of the shaftand the second compartment with the discharge opening of the shaft, saidpartition being provided with an opening interconnecting the twocompartments and spaced inwardly from said peripheral wall, said drumbeing provided in both compartments with flights which repeatedlyelevate and drop material in the compartments when the drum rotates inone direction, a discharge chute located in said second compartment andrigid with said drum, said chute communicating at its inner end withsaid second lateral shaft opposing and extending generally radiallytherefrom, said chute having an open side, said chute and the flights inthe second compartment being so disposed and arranged that some of thematerial elevated and dropped from the flights will enter the chutethrough the open side thereof while the chute is in an inwardly anddownwardly extending position to guide the received material into thesecond lateral shaft-opening.

4. A blender as set forth in claim 3 with the addition that at leastsome of said flights in the second compartment are arranged to carrymaterial over the drum axis, the open side of said chute facing oppositeto the men tioned direction of drum rotation to receive material socarried over the drum axis.

5. In a blender, ad rum mounted for rotation about a generallyhorizontal axis and including a blending compartment, means for feedingloose material into said com partment, said drum being provided aroundthe periphery of said compartment with a series of flights whichrepeatedly elevate and drop material when the drum rotates in onedirection, discharge means located near the drum axis for conveyingmaterial from the compartment, and a generally radially extending chutemounted in the compartment and rotatable with the drum, said chute beingarranged to discharge into said discharge means, said chute having anopen side and the chute and flights being so arranged and disposed thatsome of the material elevated by and dropping from the flights will fallinto the chute through the open side thereof while the chute is in aninwardly and downwardly sloping position to guide the received materialinto said discharge means.

6. A blender as set forth in claim 5 with the addition that at leastsome of said flights are arranged to carry material over the drum axis,the open side of said chute facing opposite to the mentioned directionof drum rotation to receive material so carried over the drum axis.

7. A blender as set forth in claim 6 with the addition that said chuteextends to the periphery of the compartment and has there a widthsubstantially equal to the axial extent of said compartment, the innerportion of said chute having a width less than the axial extent of thecompartment.

8. A blender as set forth in claim 6 with the addition that said chuteextends to the periphery of the compartment.

9. A blender as set forth in claim 6 with the addition that said chuteextends to the periphery of the compartment and has there a widthsubstantially equal to the axial extent of said compartment.

10. In a blender, a drum mounted for rotation about a generallyhorizontal axis and including a blending compartment having axiallyspace end walls and a pcripheral wall, means for feeding loose materialinto said compartment, said drum being provided in said compartment witha circumferential series of flights which repeatedly elevate and dropmaterial when the drum rotates in one direction, one of said end wallsbeing provided with an outlet opening spaced inwardly from saidperipheral wall, and a generally radially extending chute mounted insaid compartment and rotatable with the drum, said chute extendingoutwardly to said peripheral wall and being there provided with an inletopening facing opposite to the mentioned direction of drum rotation,said chute having at its inner end an outlet opening dischargingexteriorly of the compartment, the radial extent of said inlet openingbeing so limited that substantially none of the material dropping fromthe flights in rotation of the drum in the mentioned direction willenter the opening.

11. A blender as set forth in claim 10 with the addition that said inletopening has, at the peripheral wall, an axial extent substantially equalto that of the compartment, the inner portion of the chute having awidth less than the axial extent of the compartment.

12. A blender as set forth in claim 10 with the addition that said inletopening has, at the peripheral wall, an axial extent substantially equalto that of the compartment.

13. In a blender, a hollow shaft having axially spaced inlet anddischarge openings for material to be treated and supported for rotationabout a generally horizontal axis, a drum rigidly secured to said shaftbetween said openings, said drum including a compartment'having axiallyspaced end walls and a peripheral wall, said shaft being provided with alateral opening connecting the compartment with the inlet opening of theshaft, said drum being provided in said compartment with acircumferential series of flights which repeatedly elevate and dropmaterial as the drum rotates in one direction,

and a generally radially extending chute mounted in said compartment androtatable with the drum, said chute extending outwardly to saidperipheral Wall and being there provided with an inlet opening facingopposite to the mentioned direction of drum rotation, the radial extentof said inlet opening being so limited that substantially none of thematerial dropping from the flights in rotation of the drum in thementioned direction Will enter the opening, said chute being provided atits inner end with an outlet opening through which material entering theinlet opening of the chute is returned to the shaft for flowtherethrough toward the discharge opening there- 14. A blender as setforth in claim 13 with the addition that the inlet opening of the chutehas, at the peripheral Wall, an axial extent substantially equal to thatof the compartment, the inner portion of the chute having a Width lessthan the axial extent of the compartt ment.

15. A blender as set forth in claim 13 with the addition that the inletopening of the chute has, at the peripheral wall, an axial extentsubstantially equal to that of the compartment.

References Cited by the Examiner UNITED STATES PATENTS 2,504,378 4/1950Bell 259-3 2,638,625 5/1953 Studebaker et al. 259-3 2,797,070 6/1957Winn et al. 259-3 FOREIGN PATENTS 233,465 4/1961 Australia.

CHARLES A. WILLMUTH, Primary Examiner.

5. IN A BLENDER, A DRUM MOUNTED FOR ROTATION ABOUT A GENERALLYHORIZONTAL AXIS AND INCLUDING A BLENDING COMPARTMENT, MEANS FOR FEEDINGLOOSE MATERIAL INTO SAID COMPARTMENT, SAID DRUM BEING PROVIDED AROUNDTHE PERIPHERY OF SAID COMPARTMENT WITH A SERIES OF FLIGHT WHICHREPEATEDLY ELEVATE AND DROP MATERIAL WHEN THE DRUM ROTATES IN ONEDIRECTION, DISCHARGE MEANS LOCATED NEAR THE DRUM AXIS FOR CONVEYINGMATERIAL FROM THE COMPARTMENT, AND A GENERALLY RADIALLY EXTENDING CHUTEMOUNTED IN THE COMPARTMENT AND ROTATABLE WITH THE DRUM, SAID CHUTE BEINGARRANGED TO DISCHARGE INTO SAID DISCHARGE MEANS, SAID CHUTE HAVING ANOPEN SIDE AND THE CHUTE AND FLIGHTS BEING SO ARRANGED AND DISPOSED THATSOME OF THE MATERIAL ELEVATED BY AND DROPING FROM THE FLIGHTS WILL FALLINTO THE CHUTE THROUGH THE OPEN SIDE THEREOF WHILE THE CHUTE IS IN ANINWARDLY AND DOWNWARDLY SLOPING POSITION TO GUIDE THE RECEIVED MATERIALINTO SAID DISCHARGE MEANS.